1. Field of the Invention:
The invention generally relates to suspension systems for supporting moving loads and more particularly to an improved suspension system for an uncrowned wheel rolling on a flat track and adapted for use in supporting large track-mounted antennas.
Suspension systems for wheel assemblies employed in transporting massive loads along flat tracks tend to be plagued by problems introduced because of misalignment introduced between the surface of the track and the surface of the wheel. Such misalignment, in turn, introduces error in load distribution along contact interfaces established between the surfaces of the wheels and the tracks. It is desirable that loading along the linear area of contact which, as a practical matter, comprises a line parallel to the axis of the wheel, be symmetrical and nearly as uniform as possible. Where the loading is not symmetrical an interface moment will exist between the wheel and the track. The effect of the moment is to increase load intensity at one edge of the wheel while reducing it at the other.
2. Description of the Prior Art:
The prior art is, of course, replete with teachings of resilient members employed in coupling axles of wheels to load-bearing trucks. For example, the following patents were discovered during the course of the search conducted for the invention:
______________________________________ Brown 400,544 April 2, 1889 Rossell 2,861,522 Nov. 25, 1958 Hirst et al 2,954,747 Oct. 4, 1960 Hirst 3,191,551 June 29, 1965 Weber 3,286,653 Nov. 22, 1966 Germer 3,707,928 Jan. 2, 1973 Julien 3,818,841 June 25, 1974 ______________________________________
It is noted that the patent to Germer U.S. Pat. No. 3,707,928 discloses vertically aligned leaf springs in a suspension system employed in coupling a car body to a wheel axle. The patents to Hirst and Rossell disclose rubber springs for supporting axles for track-mounted vehicles. The patent to Weber shows that it is old to employ vertically inclined coil springs in supporting relation with the axle. The patents to Brown and Julien disclose frames for mounting axles.
Additionally, U.S. Pat. No. 3,711,055 which issued Jan. 16, 1973 to Roger K. Schulz et al discloses a load bearing apparatus for rail-mounted satellite tracking antennas, or other massive structures which utilize a four bar wheel-supporting linkage to maximize the area of contact between the supporting wheels and the rails, and hence to minimize contact stresses between the wheels and the rail.
The suspension system disclosed by the patent to Schulz et al, in effect, consists of sloping, rigid links connecting a base frame to a wheel frame with the end links thereof being pivoted in bearings. It can be shown mathematically, from data taken from engineering designs of known suspension systems for the azimuth bearing of large antennas, the maximum wheel-track loading intensityy can be increased by 39% over an ideal value. If bearing friction coefficient is increased to 0.30 the 39% increase in intensity would increase to 108%, more than twice the ideal value.
It is, therefore, the general purpose of the instant invention to provide an improved suspension system for the azimuth bearing of large antennas in which maximum wheel-track loading intensity is increased by only 1.15% over the ideal value.